The present invention relates to a propeller arrangement comprising a propeller with individual blades to be joined on a sleeve.
Thrust required for the movement of marine vehicles capable of traveling on the water such as boats, ships or capable of traveling under water such as submarines is provided by the propeller. Propellers generally comprise a hub portion and a plurality of blades connected to the hub. Surfaces of the propeller blades are generally provided with a helicoidal form and pressure is created by the compression of fluid, water, on the helicoidal surface after it is captured by the leading edge of the blade, then it accelerates over the blade and exits from the trailing edge. The path followed by the fluid over the blade and compression amount connected thereto affects the magnitude of the resulting thrust.
Propellers are conventionally cast in monolithic form and produced by being machined. In other words, blades are produced monolithic to the hub. This monolithic structure has some disadvantages. A). Blades cannot overlap each other for the removal of the propellers generally cast as a single piece from the mold and surface machining thereof and they can hardly exceed a surface area ratio of 1:1, remaining generally below the value of 1 (For example: 0.950, etc.). B). If one of the blades is damaged due to mechanical fatigue, external impact or any other reason, the entire propeller is discarded. In addition, the blades should be provided along the thickness of the hub (i.e. the depth-wise direction of the hub) in order to achieve maximum thrust from the blades arranged radially around the hub. Production costs of a very sensitive structure with such a complex geometry are high, because it requires detailed planning during and prior to the operation, benches or machines meeting the diameter of the entire propeller are required to be enormous and expensive units for fulfilling the size limits thereof.
There are known marine propellers having blades detachably connected to each other by securing mechanisms such as bolts. In this type of propellers, detachable blades are usually mounted and secured on the external surface of a cylindrical hub. Thus, hubs and blades are separately produced and then mounted for each separate boat. On the other hand, it is difficult to ensure a safe blade connection in the propellers with detachable blades. Blade connections can weaken over time.
For example, propellers with blades detachably secured to the hub are disclosed in the documents US2008/0166933, the entire contents of which is incorporated herein by reference, U.S. Pat. No. 6,537,031, the entire contents of which is incorporated herein by reference, and GB2328251A, the entire contents of which is incorporated herein by reference. Also, in the document JP 1237068, the entire contents of which is incorporated herein by reference, blades forming a propeller by means of a middle hub portion and manufacturing method of said blades and separate molding of the propeller blades are disclosed.
Propellers with detachable blades are also known in the prior art, wherein each blade is partially integral with a portion of the hub. For example, US2012114489, the entire contents of which is incorporated herein by reference, discloses a propeller with blades mountable to each other and partially comprising a portion of the hub at the joining end of the blades is disclosed. The propeller of US2012114489 should be separately designed for each separate vessel shaft and the rigidity of the blade connections is debatable.